In the traditional method of applying grout mortar to ceramic floor tile, a thin mortar is squeegeed into the crevices with a hand-held, rubber-faced trowel. Excess mortar is then washed from the surface of the tile with a wet sponge before the mortar completely dries.
This grouting technique is entirely acceptable for small surface area. However, it is labor-intensive and time-consuming for large tiled areas.
In the past, motor-driven rotary trowels have been employed to impart the desired finish surface to concrete floors. U.S. Pat. No. 2,556,983, granted Jun. 12, 1951, to W. J. Root for "CEMENT FINISHING FLOAT BLADE", and U.S. Pat. No. 2,662,454, granted Dec. 15, 1953, to M. E. Whiteman for "FLOAT TROWEL FOR CEMENT FLOOR FINISHERS" disclose machines useful for this purpose. Neither of these patents makes reference to the application of grout.
Somewhat similar apparatus is disclosed in U.S. Pat. No. 2,963,059, granted Dec. 6, 1960, to R. Grub for "APPARATUS TO SMOOTH FLOORING". This apparatus employs flexible metal blades depending from a rotating disk to smooth a floor coating. The patent contains no indication that the apparatus would be useful in troweling grout onto a tiled surface.
Machines have also been devised for the controlled application of a thin, protective coating to a flat surface. U.S. Pat. No. 3,239,871, granted Mar. 15, 1966, to R. W. LeMieux, et al. for "APPLICATOR APPARATUS" discloses such a machine for finishing and refinishing bowling alleys. The machine does not appear suitable for grouting tile.
There continues to be a need for a motorized tile grouting machine capable of rapidly grouting large surface areas.